1. Field of the Invention
The following description relates generally to poly cross linked phthalocyanine compound for solar cell and ink composition comprising the same, and more particularly to poly cross linked phthalocyanine compound beneficial for use in a near infrared absorbent having a high absorption power in a near infrared wavelength from about 750 nm to about 1,100 nm.
2. Description of the Prior Art
Conventional solar cells convert light into electricity by exploiting the photovoltaic effect that exists at semiconductor junctions. In other words, the commercial solar cells absorb energy from visible light and converts excited charge carriers thereof to electric energy. At present, the main commercial solar cells are silicon-based solar cells. For a silicon-based solar cell, there are shortcomings in that high energy costs for material processing is required and many problems to be addressed such as environmental burdens and cost and material supply limitations are involved. For an amorphous silicon solar cell, there are also shortcomings in that energy conversion efficiency decreases when used for a long time due to deterioration in a short period.
Recently, many attempts have been undertaken to develop low-cost organic solar cells, whereby development of one particular type of solar cell which is a dye-sensitized solar cell (DSSC) is accelerated that generally uses an organic dye to absorb incoming light to produce excited electrons.
The dye-sensitized solar cells have advantages over silicon-based solar cells in terms of simplified processing steps, low fabrication cost, transparency and pleochroism. The dye-sensitized solar cells can be fabricated from flexible substrates to function as cells of mobility and portability.
The dye-sensitized solar cells have lower energy (photoelectric) conversion efficiency over that of the silicon-based solar cells such that a wide range of researches are briskly under way to enhance the energy conversion efficiency. In order to improve the energy conversion efficiency, extension of wave length up to infrared regions is being waged with great concern. It is known that the energy bandgap (eV) for use in solar cells must exceed 1.4 eV (electron volt).
Meanwhile, phthalocyanine compound used as a dye in electrodes for solar cells has advantages such as high transmittivity relative to visible light, excellent selective absorption power in the near infrared region, high heat resistance, high weatherability and high thermotolerance, so that the phthalocyanine compound has a wide range of applications including ink and fields where a predetermined wave length is absorbed or interrupted.
A variety of technologies involving the phthalocyanine compound has been disclosed. For example, phthalocyanine compound and manufacturing method thereof are described in Korea Patent Laid-Open Publication No. 10-528155, the phthalocyanine compound being expressed in the following Formula 1,
where, M1 and M2 independently represent selections from non-metals, metals, metal oxides, and metal halides and may be same or different each other. R1 to R16 respectively represent a hydrogen atom, a halogen atom, a hydroxyl, an amino group, a hydroxysulfonyl group, an aminosulfonyl group, an alkyl group, an alkyl group which may have substituents of a 1˜20 carbon numbers, SR17, SR18, OR19, NHR20 or NHR21, selections which may be respectively the same or different, and where, R17 is a phenyl group which may have substituents, an alkyl group or a 1˜20C alkyl group, R18 is a phenyl group which may have a 1˜20C alkoxy group, R19, R20 are respectively a phenyl group which may have a substituent, an arylalkyl group or a 1˜20C alkyl group, R21 is a 1˜20C alkyl group which may have a substituent, and n is an integer of 0˜3.
The phthalocyanine compound having a structure of the afore-mentioned Formula 1 which has a phthalic anhydride and a urea, a metal salt or a metal chloride may interrupt an inflow of oxygen, and may be obtained by reaction at a high temperature using solvent of a high boiling point.
In this regard, it is therefore desirable to keep working on the compound showing an absorption power at a wider scope of a near infrared region.